The Citrix ADC High Availability (HA) monitoring feature (HAMON) is used to trigger a failover if a critical interface on the primary node fails. However, if an interface is administratively disabled, the HA monitoring logic considers its state to be healthy (UP). Therefore, if HA monitoring is enabled on an interface that has been administratively disabled on the primary node, the system will never detect a failure on that interface, and a failover will not be initiated. This directly causes the behavior described in the scenario, where the failover does not work as expected.

A. HA monitoring on the secondary node is irrelevant for triggering a failover. The health of the primary node's monitored interfaces determines if a failover should occur.

B. Independent Network Configuration (INC) mode is a valid configuration for specific network topologies and does not inherently cause failover to fail. It simply prevents certain network settings from being synchronized.

D. As long as HA heartbeats are received on at least one interface, the secondary node considers the primary node to be active and healthy, and no failover is triggered.

1. Citrix ADC 13.1 Product Documentation

"High availability" > "High availability deployment modes" > "Monitoring on a high availability pair".

Reference for Correct Answer (C): The documentation states

"The health of an interface that is administratively disabled is not monitored. If HA MON is enabled on an interface and you then disable that interface

the health check for that interface always returns UP." This confirms that a disabled

monitored interface will prevent a failover.

2. Citrix ADC 13.1 Product Documentation

"High availability" > "High availability nodes".

Reference for Incorrect Answer (A): The documentation explains that failover is triggered based on the health of the primary node. The secondary node's status is passive until a failover event occurs.

Reference for Incorrect Answer (D): This section details heartbeat exchange: "If heartbeats are not received on any of the interfaces from the peer node for a predefined time interval

the node is considered to be down..." This implies receiving heartbeats on some interfaces is a healthy state.

3. Citrix ADC 13.1 Product Documentation

"High availability" > "High availability setup in different network configurations" > "Independent network configuration".

Reference for Incorrect Answer (B): This section describes Independent Network Configuration (INC) as a feature for specific use cases

not as a cause of failover failure. It states

"In an HA setup

you can configure a SNIP address or a VLAN on one node without having that configuration automatically propagated to the other node."